  The integration of NMR and high pressure technique brings unique
opportunities to study electronic, structural and dynamical properties under
extreme conditions. Despite a great degree of success has been achieved using
coil-based schemes, the contradictory requirement on sample volume of these two
techniques remains an outstanding challenge. In this letter, we introduce
diamond nitrogen-vacancy (NV) centers, as the source and probe of in-situ
nuclear spin polarization, to address the sample volume issue. We demonstrate
hyperpolarization and coherent control of $^{14}$N nuclear spins under high
pressures. NMR spectra of a micro-diamond are measured up to 16.6 GPa, and
unexpected pressure shift of the $^{14}$N nuclear quadrupole and hyperfine
coupling terms are observed. Our work contributes to quantum sensing enhanced
spectrometry under extreme conditions.
