An accurate and stable displacement sensor that reads through coated metal substrates achieves better than one micron accuracy includes: an electromagnetic coil positioned in a first enclosure; (ii) means for generating a magnetic field from the electromagnetic coil; (iii) a second enclosure which is spaced apart from the first enclosure, wherein the second enclosure includes dual magnetic sensors, such as fluxgate sensors, that are configured to measure the magnetic field; and (iv) means for calculating the separation between the operative surfaces of the enclosures from magnetic field measurements. A permanent magnet can be used instead of the electromagnetic coil and associated driving energy source. A precise displacement measurement is given by a mathematical function (such as the ratio or difference) of the two magnetic sensors demodulated signals. The displacement sensor can be mounted on a maneuverable C-frame to monitor the caliper of anodes and cathodes produced for lithium ion batteries.