A magneto-optic linear-displacement (MOLD) sensor is reported for measuring linear displacements of the surfaces of materials remotely. It is based on observation of temporal changes in the intensity of the reflected polarized light beam, which passes through a magneto-optic thin garnetfilm with controlled periodical displacement of one domain wall. The MOLD sensor allows observation of linear displacement of a material located remotely from the laser and detector with a spatial resolution of 4μm.