  We report on the dynamics of the Rabi oscillation and the Larmor precession
of $^{15}$N nuclear spin using nonselective short microwave pulses for
initialization of $^{15}$N nuclear spins. We observe the Larmor precession of
$^{15}$N nuclear spin depending on the angle between the applied magnetic field
and the axis of the nitrogen vacancy center. We propose to utilize the change
of the Larmor frequency of the nuclear spins to detect static magnetic fields
at high sensitivity. Our results may contribute to enhancing the sensitivity of
dc magnetic fields and devising novel protocols using $^{15}$N nuclear spin in
nitrogen vacancy centers in diamonds.
