I found out that many devices as PCs, TVs, cellphones and more can use a technology called ultrasonic cross-device tracking. This means that there are ultrahigh sound frequencies which propagate from device's speakers and are received by nearby microphone embedded in other devices. This allows to transfer data.
Is there a way to capture these signals? Is there some app maybe that listens to Ultrasonic frequencies and let's me know what type of info is been transfered?