Can I use an external microphone?

It is very likely that Hi-Q MP3 Voice Recorder can record from an external microphone from the headphone port. 

Almost all of the newer microphones uses CTIA / AHJ standard. Almost all phones released after 2013 uses the same standard, so it is likely to work. However, please try it first using the Free version of Hi-Q MP3 Voice Recorder.

If it still does not work, you might want to change the option at the app Settings > Recording > Mic selection to Device default.