A probe with plural output channels for sensing the movement of a body of magnetic material. The probe includes a magnetically energizable pole piece and a plurality of electrically conductive circuits, coupled to the magnetic pole piece, such that a change in magnetic flux in the pole piece caused by movement of the body relative to the pole piece induces a voltage in each of the circuits. The electrically conductive circuits are wound around each other in a symmetrical fashion such that in the vicinity of the magnetic pole piece each circuit experiences substantially the same change in magnetic flux. A probe of this type provides a plurality of substantially identical output signals and is easy to manufacture and replicate.