  Dust polarization observations are a powerful, practical tool to probe the
geometry (and to some extent, the strength) of magnetic fields in star-forming
regions. In particular, Planck polarization data have revealed the importance
of magnetic fields on large scales in molecular clouds. However, due to
insufficient resolution, Planck observations are unable to constrain the
B-field geometry on prestellar and protostellar scales. The high angular
resolution of 11.7 arcsec provided by NIKA2-Pol 1.15 mm polarimetric imaging,
corresponding to $\sim$ 0.02 pc at the distance of the Orion molecular cloud
(OMC), makes it possible to advance our understanding of the B-field morphology
in star-forming filaments and dense cores (IRAM 30m large program B-FUN). The
commissioning of the NIKA2-Pol instrument has led to several challenging
issues, in particular, the instrumental polarization or
intensity-to-polarization (leakage) effect. In the present paper, we illustrate
how this effect can be corrected for, leading to reliable exploitable data in a
structured, extended source such as OMC-1. We present a statistical comparison
between NIKA2-Pol and SCUBA2-Pol2 results in the OMC-1 region. We also present
tentative evidence of local pinching of the B-field lines near Orion-KL, in the
form of a new small-scale hourglass pattern, in addition to the larger-scale
hourglass already seen by other instruments such as Pol2.
