A magnet is surrounded by an invisible field of magnetic energy. Although we now know the physical reason for that energy field, to your dreaming mind, a magnet in a dream simply represents something that is surrounded by a powerful force that might even be considered magical.
A magnet in a dream can represent your unrealized potential. If you dream about a magnet, it can be a sign that you have powers that you did not know existed.
Magnets attract and repel things, so a dream about a magnet can be telling you something about your ability to attract or to repel other people. A dream about a magnet can say something about the amount of influence you have on others.
A dream that a large magnet is dragging something away from you can mean that you feel that forces that are out of your control are taking something away from you in real life.