Methods, apparatuses, and systems for operating an electronic device as a web camera are disclosed. The disclosed embodiments relate to features that enable a user to operate a mobile device as a webcam. A smartphone case can hold a smartphone and be attached to a display, such as a laptop monitor or a flatscreen monitor, with a camera of the smartphone pointed at the user. The smartphone case can include a magnet, which triggers a Hall effect sensor inside the laptop or flatscreen monitor. The sensor can be used to trigger software that enables the smartphone and laptop or computer to pair with each other, e.g., by a Bluetooth handshake. The laptop or computer can accept a Wi-Fi or physical signal, such as via USB, from the smartphone and treat that input as a video stream into the laptop or computer.