We consider a child sitting in a rotating carousel with a charged ball and a bar magnet in his hand. This child can be seen as an electron rotating around the center of the carousel, which can be seen as the nucleus.
Spin dipolar contribution
This contribution is achieved by the child holding the bar magnet. It produces an electric field that reaches the center of the carousel. The magnetometer can be used to measure the amount of magnetic field in the center.
The child holds a charged ball while rotating. Rotating a charged object can be seen as a current loop, which can create a magnetic field. The magnetometer can be used to measure the presence of magnetic field.
Fermi contact contributions
This contribution is difficult to explain with this analogy, because I presume that the child does not go in the center of the carousel to put electron-like objects in there.