How to detect the present of bluetooth device for HC 05

My aims is to trigger certain other functions once detects specified or any unknown bluetooth transmitters ,such as bluetooth earphone, connection is not needed.

My Arduino device will not be attatched into computer so that it can not go into AT mode except the first time set up.

Base on Hc 05, or any other you may recommended, is there any similar code for reference?

I appreciate and thanks for your help!!!

You might find a BLE device more suitable for this.