Our challenge: get an iPhone camera as close as possible to the webcam, for the perfect eyeline. The solution that often works best is very simple, a gaffers tape mount!
Gaff tape is a filmmaker's best friend. It tears like strong paper or cloth.
Try not to let the two sticky sides touch unintentionally or they may be become permanently stuck. (ruler is for reference only)
Simple tricks like this are a big deal during the coronavirus crisis, since subjects are often the ones setting up their shots. See below for a video filmed with our gaff-tape method.