Ghost Detector is an entertainment app. It runs a human pose-detection model — the same class of model used by fitness apps — and draws a skeleton over arrangements of features it finds human-shaped. Pointed at an empty room it will sometimes lock onto a coat rack, a shadow or a fold in a curtain. That is the model being wrong in an interesting way, and it is the point of the app.
Ghost Detector makes no claim to detect anything supernatural. It detects human-shaped forms and nothing else. Nothing is drawn on a timer and no figure is ever fabricated: if a skeleton appears, the model produced it from the pixels in front of the lens. It must not be relied on for decisions of any kind.
The app is licensed to you for personal use. The photos, recordings and session logs you make are yours to keep and share.