Studying the polarization properties of penumbral microjets that have the shortest durations requires spectropolarimetric observations with the fastest temporal cadence possible and is currently a challenging task. Here, we approach this task using fast-cadence spectropolarimetric measurements of the Ca II 8542 A line made with the CRISP instrument at the Swedish 1 m Solar Telescope. We exploited the diagnosis capabilities of this line to retrieve the magnetic field configuration and its evolution in the upper photosphere and low chromosphere by applying the weak field approximation to its wings and line core wavelengths respectively. We found that the short-lived microjets are associated with a transient perturbation in the photospheric magnetic field and sometimes they show clear but weaker changes in the chromospheric field as well. We will describe the different types of evolution that were identified.