If you asume that the center of the carousel is the nucleus than you can put there the magnetometer so it can measure the magnetic field of the different hyperfine interactions. A child is on a horse of the carousel and holding a bar magnet. The child can now be seen as an electron with a spin and and makes a magnetic field now. This gives the dipole term. If the child is holding a electrically charged ball, than this will create a current around the magnetometer. This gives the orbital term.