The present invention is directed to a sensor with a body and a magnetic field sensor. The body includes a plurality of structures arranged in a first direction to effect a periodically varying magnetic field upon movement of the body in the first direction. The magnetic field sensor is configured to detect components of the magnetic field in a second direction and in a third direction, wherein the magnetic field sensor is arranged adjacent to the body such that the second direction is perpendicular to the first direction and such that the third direction is perpendicular to the first direction and to the second direction.