A program to simulate an oscilloscope, works with arduino.
You'll need the python serial module.
Open in the arduino ide the .ino file and load it.
Connect the arduino to the thing you want to monitor to the A0 port (and GND if needed)
Start the program by typing python3 osci.py /dev/ttyATC0 (note: the serial port might change)
Use the buttons to select either raw inputs or fft elaboration