Magnetic poles are different from geographic poles, and when a compass is used, the compass points to the magnetic north pole instead of the geographic north pole.
There is a shift between the north-south (orange line) and the geographical north-south (black line). Illustrations from cyberphysics.co.uk.
The north-south magnetic poles are part of the Earth's magnetic field, and the magnetic poles are the endpoints (start and end points) of the Earth's magnetic field lines. On the other hand, the geographical north is related to the rotation of the Earth. If you imagine a "stick" passing through the earth representing the earth's axis of rotation, then the geographic north pole is where the north of the stick leaves the earth's body. From the geographical north, the Earth's polar star, the North Star, is overhead (although not just overhead, because it is not exactly above the geographic north).
To clarify this, on January 16, 1909, explorers from the southern continent of Antarctica—Douglas Mawson, Alistair McKay, and Edgeworth David—were near the geomagnetic south pole. Three members of Ernest Shackleton's Antarctic expedition — David the Royal Sword, Douglas Mawson, and Alistair McKay — held up a British Empire flag to "pose" to commemorate the moment they thought they had reached Earth's magnetic south pole. They only left the McMurdo Strait, on the edge of the Antarctic continent, four months ago.
By the way, magnetic south is different from the geographical south of the earth (just as magnetic north is different from the north pole). The expedition of 1908-1909 took place a century ago, when a team led by Norwegian explorer Roald Amundsen reached the geographic south pole on December 14, 1911, before scientists realized that Earth's magnetic poles were hovering or moving around the Earth's surface.
A challenging trip to Antarctica
Like all Antarctic journeys in the early 20th century— when Earth's poles were discovered and explored — the search for Magnetonan was arduous and challenging. The men had to drag their own bulky sleighs by hand through an area of completely unknown risk. The cracks—the cracks deep in the ice—slowed them down. When the journey takes longer than expected, people have to reduce their supply consumption.
But by early January 1909, the team had reached the Polar Plateau, where the thin air made breathing extremely strenuous, and on January 11, David recorded a temperature of -12 F (-24 C). Finally, on Jan. 15, when Mawson calculated that they were about 13 miles (21 km) away from Magnetinut, the men unloaded their heavy gear and fired a "final blow" at a point on Earth at 72° 25' south latitude and 155° 16' east longitude.
They raised the British flag and took pictures, and then they immediately began to return to the Nimrod ship, which had taken Shackleton's team from New Zealand to the southern continent of Antarctica the previous year.
Over time, the position of the magnetic south pole or inclination. Direct observation versus model predictions. Image courtesy of INOAA.
Mawson later realized he had ignored some important calculations made by another researcher a few years earlier. In 1913, Royal Sword David admitted that their team had only reached "the outlier of the main magnetic pole" and not the true magnetic south pole itself.
Even so, their heroic efforts have stood out in the history of science and in polar exploration.
Wandering poles
Even if they had found the true south magnetic point in 1909, it would no longer be the magnetic south pole of today. Due to changes in the Earth's magnetic field, the magnetic north and south poles drift every year.
The location of the Antarctic magnetic pole in 2020 — the last date we can find — is 64.07°S, 135.88°E. This figure comes from the Australian Antarctic Programme. This map from NOAA shows the magnetic south pole off the coast of the Antarctic continent in 2020, located in the Southern Ocean around the continent.
On January 16, 1909, explorers from the southern continent of Antarctica—Douglas Mawson, Alistair McKay, and Edgeworth David—were near the geomagnetic south pole. Image from Wikimedia Commons.
Importantly, the geographic north is associated with the rotation of the Earth. If you imagine a "stick" passing through the earth representing the earth's axis of rotation, then the geographic north pole is where the north of the "stick" leaves the earth's body. From the geographical north, the Earth's polar star Polaris is overhead (although not just overhead, because it is not exactly above the geographic north).
So the magnetic north pole and the geographic north pole don't match because they describe different aspects of the Earth.
Conclusion: On January 16, 1909, the Shackleton expedition in Antarctica believed they had found the magnetic south pole. The magnetic south pole and north pole drift every year.
reference
Shackleton expedition to magnetic south pole
https://earthsky.org/human-world/this-date-in-science-shackleton-expedition-discovered-magnetic-south-pole/