Localized magnetic fields are measured at frequencies into the microwave (GHz) regime using a conductive loop that is integrated on a vibratable member, such as a cantilever. Driving an alternating current at a first high frequency through the loop produces a high frequency alternating magnetic dipole at the same frequency as the current, with the alternating magnetic dipole normal to and centered within the loop. The alternating magnetic dipole at the center of the loop mixes with a sampled alternating magnetic field at a second high frequency at the center of the loop, resulting in application of a mechanical force to the loop and vibratable member. The vibratable member vibrates when the difference between the frequency of the loop current and the frequency of the sampled alternating magnetic field equals the resonant frequency of the vibratable member.