Audio input control

I have downloaded V 2.0.000016 of Blackmagic Camera on my iPhone 15 Max Pro. I am using a noise cancelling Bluetooth headset of the iPhone 15Max Pro for voice to one channel and want to ALSO use the cell phone's mic- this would allow capture of my voice as well as ambient sounds as I am riding the ATV recording videos. I see the software says it will record audio as stereo or four tracks, but how to set the headset on one channel and phone mic on another channel?