A measurement inside a specimen is performed by providing a nanoscale FET probe comprising a cantilever element and a nanowire extending from the cantilever element. The nanowire is electrically connected to the cantilever element at at least one of the ends of the nanowire. The nanowire is coated along at least part of the length thereof with molecules of a capture agent. The cantilever element is moved to insert the nanowire onto the specimen. An electrical property of the nanoscale FET probe is monitored to detect binding events between the capture agent molecules and an analyte of interest inside the specimen.