Stalkerware is a type of malware that disguises itself as a useful app while hiding its ulterior motives. Whether disguised as a fun game or a parental controls software, when installed on your device and given permissions, this type of software is a dangerous and unethical tool that anyone with physical access to your smartphone can install. Allowing the user to track the location of the device, read and intercept all messages and calls being sent to and from it, and even accessing any files present on the device, stalkerware is a real threat to your privacy.
However, there are some simple ways to detect such malware and stop it from stealing your information. The most simple of these is to download a mobile antivirus, such as the Kaspersky Mobile Antivirus to detect these applications. Alternatively, you can frequently check battery and performance statistics, looking for apps using exorbitant amounts of resources than they should be. In order to analyze what information is being sent to and from the device, consider using a device, such as a TinyCheck detector. For more information about stalkerware and how to keep it at bay, see the post by Kaspersky detailing it further.