How to measure frequency

I ordered a Pokit Pro because I loved that it had an oscilloscope. After receiving it, I tested it with AC 220V voltage and got good results and waveforms. But when measuring the audio signal (at the speaker base) of the Radio, no signal appeared. Measuring the frequency of 32Khz at the quartz pin also does not show any frequency. Please show me how to measure and what is the maximum frequency that Pokit Pro can measure?
Thank you!