We present spectropolarimetric observations of an on-disk condensation event obtained with Sunrise/SCIP in the Ca II 854.2 nm line. The event occurred during the coalescence of two pores of the same magnetic polarity, accompanied by coronal brightenings that indicate magnetic activity in the loop system before the appearance of the condensations. We identify the material through red-wing absorption signatures and infer its properties using a two-stage approach that combines spectropolarimetric inversions and Doppler-velocity fitting. Good fits were obtained for about 1400 profiles (~60% of the detected pixels), yielding chromospheric temperatures (5900--9100 K, mode near 7400 K) and line-of-sight velocities of 5--45 km s-1 (mode near 14 km s-1). We then apply the weak-field approximation in narrow spectral windows centered on the inferred Doppler shifts, obtaining BLoS values from approximately -100 to -900 G in the coronal rain material. To interpret the large spatial variation of BLoS, we compare the observations with a force-free magnetic field extrapolation and find a loop whose projected Bz variation reproduces the observed trend along the traced path. The inferred loop geometry also yields free-fall speeds consistent with the measured velocities. These results show that high-resolution spectropolarimetry of on-disk coronal rain can provide constraints on the thermodynamic and magnetic properties of cool plasma in coronal loops. The comparison with the extrapolated field also suggests that the observed BLoS trend is compatible with a plausible loop geometry.