Center of the carousel can be understood as the nucleus with a magnet in the central axis of it, that will represent the nuclear magnetic field due to nuclear spin interaction with the electron cloud’s magnetic momentum u, represented as the rotating child with the electrically charged ball in child’s hands that the child is rotating as well around it’s axis (electron spin). Due to the electron cloud interaction with nucleus the nucleus is influenced (bar magnet & electrically charged ball).
Depending on the carousel’s rotation direction with respect to the bar magnet’s orientation and the rotation direction of the charged ball in the child’s hands, the magnetometer can measure differing magnetic moments
The orbital movement of carousel and the rotation of the charged ball represents the fine structure phenomenon in the atom structure (L-S coupling)
The L-S coupled movement of the charged ball around the bar magnet represents the hyperfine structure phenomenon in the atom (I-J coupling)