When you download apps from Google Play Store, they are usually safe and free of malware. This is because Google has a stringent policy against infected apps. However, there are a lot of ways by which your apps could be leaking information
about you without your knowledge. For example, your smartphone could be sending out ultrasonic tones right now, and you would not know. These tones would then get picked up by other devices, and this your information could be leaked.

Continue reading: http://www.tutloaded.com.ng/2017/07/18/ultrasonic-tones-could-secretly-be-leaking-your-information/