https://www.techradar.com/news/future-iphones-could-have-dual-lens-features-with-a-single-lens-camera

The iPhone X and iPhone 8 Plus already have dual-lens cameras, but there’s evidence that in future Apple might be able to achieve some of the same things with a single lens, which could perhaps be used on lower-cost models, or on the front-facing camera, which is still single-lens on all Apple’s phones.

The evidence takes the form of an Apple patent, which details an ‘image sensor with in-pixel depth sensing’. As ever with patents it gets rather technical, but essentially the system could form photo detectors in two pixels, which could then be used to gather information, such as depth.