Someone here posted an interesting sampler patch for playing external sound via onboard FX. I haven’t had the chance to download it, but when fiddling with my OP-1, I figured the same principle can be applied to any engine. People have already posted variations of this trick, but clearing it up will probably help.
Chose Element LFO, set source to microphone, amount to 100, destination to the last setting (looks like a note and a speaker), and set param destination to blue (controls envelope amplitude).
Now when you press a key it will play the source “through” the engine. The result varies depending on the engine settings. FM produces recognizable sound with an interesting distortion.
If you want to get “clean” sound, take any sample from pre-loaded ones (e.g. Acidrone) and move the loop points to the same peak. You can also not move the loop points, in which case the sample will be AM-modulated by the input.