Meet the Delta X 100/6: a counter surveillance system that lets you detect all kinds of RF listening devices around you. It can also detect GSM, 3G, 4G/LTE, Bluetooth, WiFi, and other digital surveillance tools. It has multiple modes and higher sensitivity than comparable models.
The unit has an update rate of 2000-3000 MHz per second. The data is visualized on the screen and the operator is provided with visual and audio notification to locate bugging devices. Not a cheap unit though.