Digital holography (DH) in microscopy became an important interferometric tool in optical metrology when camera sensors reached a higher pixel number with smaller size and high-speed computers became able to process the acquired images. This allowed the investigation of engineered surfaces on microscale, such as microelectromechanical systems (MEMS). In DH, numerical tools perform the reconstruction of the wave field. This offers the possibility of retrieving not only the intensity of the acquired wavefield, but also the phase distribution. This review describes the principles of DH and shows the most important numerical tools discovered and applied to date in the field of MEMS. Both the static and the dynamic regimes can be analyzed by means of DH. Whereas the first one is mostly related to the characterization after the fabrication process, the second one is a useful tool to characterize the actuation of the MEMS.