Can I take a photo of the user while they are filling a form?

I was contacted to make an application to record the user's facial expressions while the user is filling out a form.

The functionality is that when the user or the nurse who is assisting them presses a button on the form, a photo is automatically taken.

I barely worked with react native and due to the requirements I recommended to the client to do a web application, but he insisted on making a mobile app a form or on the contrary. When asking for permission to take a photo, the application closes and opens the camera.

I barely worked with react native and due the requirements I recommended to the client to do a web application, but he insisted on making a mobile app