On my PC I have a PreSonus AudioBox that allows for the use of a microphone or plugging directly in with a pickup. There are other companies that manufacture similar products.

I have one of these for use with my iPhone:

Shure MVI

Works basically as the PreSonus Audio box - either plug in your pickup or a microphone.

And, again, there are other manufacturers. These are just my choices.

...Deb