  Nonreciprocity can not only generate quantum resources, but also shield noise
and reverse interference from driving signals. We investigate the advantages of
nonreciprocal coupling in sensing a driving signal. In general, we find that
the nonreciprocal coupling performs better than the corresponding reciprocal
coupling. And we show that homodyne measurement is the optimal measurement. A
single non-reciprocal coupling can increase measurement precision up to 2
times. Using $N$ non-reciprocal couplings in parallel, the measurement
precision can be improved by $N^2$ times compared with the corresponding
reciprocal coupling. In a non-zero temperature dissipative environment, we
demonstrate that the nonreciprocal quantum sensing has better robustness to
thermal noise than the reciprocal quantum sensing.
