Yes, you can. CodeSignal has webcam and microphone access through the browser, so any application is recognizable by the browser will work with CodeSignal.
A number of applications are available that allow you to use a phone as a microphone or camera. Below are a few of them:
Apps to use a phone as a microphone
- Microphone Live (iPhone)
- WO Mic (Android)
Apps to use a phone as a webcam
- Reincubate Camo (iPhone)
- DroidCamX (Android)