# Magnetometer

The **magnetometer** is a sensor that measures the magnetic field. In our devices, the magnetometer acts like a **compass** as it measures the ambient magnetic field of the Earth. This can be used to determine position changes (e.g. door openings, the most common magnetometer use case). The magnetometer is only available in the [Door eCompass](https://simplehw.eu/shop/product/simplepack-4-0-plus-door-ecompass-91?attrib=45-89\&attrib=#attr=603,602,601,600,605,606,604,610,611,613,614,608,609,607,617,618,616,615,599) & [Full](https://simplehw.eu/shop/product/sp31ppa-fl-lga0w-fb-stck-simplepack-4-0-plus-full-42?attrib=45-89\&attrib=#attr=316,353,350,351,301,309,310,308,317,315,318,319,312,313,311,322,323,321,320,299) versions of the **SimplePack**.