Magnetism is an upgrade that is unlocked from completing Ghost Hunter Jesse's Questline.
Magnetism causes items dropped by Ghosts to be drawn towards (and eventually collected by) the player so that they do not need to walk over to collect them.
Permanent Magnet[]
The Permanent Magnet is an Upgrade unlocked from completing Remnant Jack's questline.
The Permanent Magnet permanently applies the Magnetism upgrade for you, even after Rebirthing.