noisy power supply for electric guitar pedal
Guitars, guitar effects and amps catch all available noise due non-balanced signals, high input impedances of the devices and ground loops. In addition the quitar itself has a pickup coil. 

You have at least your amp and power supply for effects connected to mains AC. "they are isolated!" you can say. They aren't, there's very likely a strong capacitive connection inside the power supplies.

You have a good HF noise transmitter in your power supply box. Test it with an AM radio. I bet you haven't any metal shield inside the plastics. Check also, is there any real input filter which protects your mains AC. I have seen (=purchased) a good looking  power supply where the input filter was decorative only. The ferrite core was plastic. The transformer fortunately was functional.  There was no metal shield around the circuit board. All certifications were printed well. One could easily find the right stamps for every application.

Run your effect with a battery and find what actual connections are needed for the power supply to start the noise. You may be able to filter them. But if you are in a hurry, get a linear (=non switch mode) regulated power supply as already suggested.