Polarimetric observations in optical and longer wavelengths are crucial to understand the properties and the distribution of dust as well as to map the magnetic field orientation in different Galactic environments such as star clusters, star-forming regions, molecular clouds, etc. Molecular clouds or Star forming regions are the critical sites for studying stellar evolution and understanding the star formation process. Observations in the optical regime are restricted to low extinction Galactic environments, limiting their applicability in dense star-forming regions. In contrast, facilities operating at longer wavelengths such as the James Clerk Maxwell Telescope (JCMT) are playing a transformative role in the study of star formation. Among these, dust polarization has emerged as a powerful diagnostic tool for probing magnetic fields and the properties of interstellar dust. Starlight becomes linearly polarized by aligned, asymmetric dust grains in the interstellar medium, seen in optical wavelengths through extinction and at longer wavelengths via polarized thermal emission. The leading theory of grain alignment is based on radiative torques (RATs) arising from the interaction of left-handed and right-handed photons with irregular dust grains. In this talk, I will present results from JCMT sub-mm polarization data, aimed at probing the magnetic field and grain alignment in Serpens Main molecular cloud.