The magnetometer is used to measure the magnetic fields.
The center of the carrousel is the nucleus.
There are two contributions that are easy to visualise:
Holding the bar magnetic outside the carrousel represents the spin-dipole contribution.
Giving the child riding the carousel the electrically charged ball represents the orbital contribution.
The Fermi contact contribution is more difficult, I would represent it by sticking the bar magnet inside the electric ball and putting that at the center of the carrousel.