This thesis explores the secrets of galaxies during cosmic noon, a transformative epoch around redshift z=1-3 when star-formation activity within galaxies was at its peak. Leveraging gravitational lensing as a cosmic telescope, the study delves into the details of high-redshift galaxies and their star-formation characteristics at small spatial scales. Key questions addressed include the spatial distributions of critical galactic parameters (stellar mass, star formation rate, molecular gas mass, and dust mass) in distant galaxies, the manifestation of the Kennicutt Schmidt (KS) law at integrated and sub-kiloparsec scales in the early Universe, and the intrinsic properties of star-forming clumps and giant molecular clouds (GMCs) in high-redshift galaxies.