We put a the child with the electrical ball inside the carousel. The carousel starts spinning, so the child starts doing circles around the center of the carousel, and obviously the charged ball too. Then, a current is created, and due to that, a magnetic field appears inside the carousel.
If we put the magnet bar in the center of the carousel, and we measure with the magnetometer the field, we will see that depending on the velocity of rotation, the position of the child in the carousel, and the direction of rotation, the field measured will variate, leading to a more stable or unstable interaction between the magnetic bar and the generated magnetic field due to the current.
This variations in the stability of the magnetic bar can be comparable with the splitting that appears in an atom due to the hyper-fine interaction, because depending on the position of the child (electron orbital) and the direction of rotation (spin) the bar magnet stabilize or not (different energy levels appear).