We put a child with the magnetometer at the center of the carousel. On one of the horses, we attach the magnet and the charged ball. There are three contributions:
1) First, the electrons have a spin and we can therefore compare them to bar magnets that generate field. These fields reach to the position of the nucleus and contribute therefore to the hyperfine field. (spin-dipolar term)
2) Next, the charge of the electrons that orbit the nucleus generate a field, since we can view it as a current around the nucleus. This is represented by the charged ball.
3) Finally, the Fermi contact contribution is a magnetic field at the position of the
nucleus due to the presence of electrons inside the nucleus. This is not represented and rather difficult to imagine classically.