Focusrite to iPhone question!

Hi.

I want to record into GarageBand on my iPhone 12 Pro Max. I’d like to get the focusrite scarlet 2i2. My question is will I be able to monitor and hear the effects in GarageBand and Tonebridge?

I tried this with my mustang micro amp and it connected and recorded but I could only hear the micro amp effects, not GarageBand. Also there was a dreadful hum when I plugged the charger in which you have to do?!

Thanks.