Why does a compass needle get deflected when brought near a bar magnet?

Hint: A compass is made by using a magnetized piece of iron, which points towards the poles of the Earth. When another magnet is brought near, the compass will point towards the other magnet as its field is stronger than the Earth’s magnetic field at that point. It works mainly on the basis of deflection due to the Earth's magnetic field.

Complete step by step answer:
Refer to the below figure for a proper explanation

In the above figure, there is a bar magnet with north and south poles denoted by N and S and also it has a magnetic needle with a compass and we can see that the pink portion both inside the needle and the bar magnet represents the north pole and the white portion represents the south pole. It can be seen that the north-pole in the magnetic needle is always deflected towards the south pole of the bar magnet and vice versa.
A compass needle gets deflected when brought near a bar magnet because a magnetic compass can be considered as a pole, and the magnet creates a field. If we place the two at rest, then the compass will be reflected in a direction, and it will be constant. But if you move the magnet, the flux lines generated will be altered, and the magnetic needle experiences a force and deflects as long as you move the magnet. And it can be understood by serving the field lines of a magnet. They are never the same at two points on coordinate axes (on opposite sides, magnitude is the same, but the direction is different). And like this, if we consider moving the magnet, the resultant field at the place of a compass will change. So there is a change in direction or magnitude, and it deflects near a bar magnet.

Note:
Since the compass needle is a tiny magnet, its direction can be altered very easily by any magnet placed close enough to it. If we move the magnet around the compass, its needle will no longer point at the North magnetic pole, but it will follow your magnet. Based on the orientation of your magnet, one of the needle tips will be attracted, and the other repelled.