If you are applying an AC signal then you need an oscilloscope to observe waveforms.
You can set the trace to start a sweep when triggered by an external signal as you apply it to the diode.
Or you can set the beam to show X/Y display. It will automatically create a graph-like display of the signal coming to the vertical input, versus the signal coming to the horizontal input.
Does your diode have a reverse V rating of 50V or higher? You may not read anything if you apply 5V reverse bias, not even a microamp.