Some embodiments of the present disclosure discuss an apparatus comprising a transceiver configured to generate and/or receive radio frequency (RF) electromagnetic signals, one or more antennae configured to radiate the generated RF electromagnetic signals toward a surface and to output signals corresponding to received reflections of the RF electromagnetic signals, and a processing circuitry configured to process the received reflections and/or the output signals so as to determine change in position of the apparatus with respect to the surface. The apparatus may be incorporated into a wearable garment and/or an adhesive patch, and it may be attached to an outer surface of a human or an animal body.