I really like to see the automatic Z correction doing it's job during prints. To see the tiny movements of the Z correction (Is it working? Is my bed level?), you can just clip this print to an unused part of the leadscrew. No tools or magnets needed. Before that, I used a paperclip but it came loose. Works fine on Prusa Mini with a 8mm leadscrew. Please let me know, if you need other dimension.

You don't need to print something to test the functionality: Just do a Automatic Mesh Bed Leveling and then move the X and Y axis via menu and you'll see the tiny rotations on the leadscrew.