The present disclosure relates to a method and system for monitoring a wellbore object using a reflected pressure signal. The method discloses providing at least one pump for performing hydraulic fracturing or a source of hydraulic pulse so that pressure signal propagates along the wellbore and reflects from the borehole objects; providing pressure sensor at wellhead; preprocessing of registered reflected pressure signal and pump noise; transforming the registered reflected pressure signal and pump noise from the frequency domain into time-frequency representation with Short Time Fourier Transform (STFT), computing a pump noise mask; applying the pump noise mask to the STFT representation to obtain a filtered reflected pressure signal; processing of the filtered reflected pressure signal for determining the reflection time from the downhole object, calculating the depth of the downhole object from reflected pressure signal by multiplying of the reflection time by the pressure signal propagation velocity. This method allows to perform wellbore monitoring without stop of current operations.