Gravitational microlensing is a powerful method for investigating compact dark objects in the Galaxy. However, analyses based solely on photometric light curves are limited by degeneracies between lens mass, distance, and transverse velocity, since photometry mainly constrains the Einstein timescale that merges several parameters into a single observable. These limitations can be alleviated by higher‑order effects such as parallax, astrometric shifts, and finite‑source effects. When the source’s angular size becomes significant, the point‑source approximation fails and microlensing induces polarization signals through differential magnification across the stellar disc and circumstellar envelope, providing observables beyond photometry. This polarimetric framework applies to both standard and non‑standard microlensing scenarios, including axion stars or axion–photon couplings, and by combining photometric with polarimetric data it reduces parameter degeneracies and opens new directions for probing compact dark matter candidates, providing a solid basis for future investigations.