Context. It is theoretically possible for rings to have formed around extrasolar planets in a similar way to that in which they formed around the giant planets in our solar system. However, no such rings have been detected to date. Aims. We aim to test the possibility of detecting rings around exoplanets by investigating the photometric and spectroscopic ring signatures in high-precision transit signals. Methods. The photometric and spectroscopic transit signals of a ringed planet is expected to show deviations from that of a spherical planet. We used these deviations to quantify the detectability of rings. We present SOAP3.0 which is a numerical tool to simulate ringed planet transits and measure ring detectability based on amplitudes of the residuals between the ringed planet signal and best fit ringless model. Results. We find that it is possible to detect the photometric and spectroscopic signature of near edge-on rings especially around planets with high impact parameter. Time resolution ≤7 min is required for the photometric detection, while 15 min is sufficient for the spectroscopic detection. We also show that future instruments like CHEOPS and ESPRESSO, with precisions that allow ring signatures to be well above their noise-level, present good prospects for detecting rings.