Disjointness of the M\"obius Transformation and M\"obius Function

We study the distribution of the sequence of elements of the discrete dynamical system generated by the M"obius transformation $x \mapsto (ax + b)/(cx + d)$overafinitefieldof$p$ elements. Motivated by a recent conjecture of P. Sarnak, we obtain nontrivial estimates of exponential sums with such sequences that imply that trajectories of this dynamical system are disjoined with the M"obius function.