Detection of transponder/transceiver

"Implants" can range from RFID tags embedded in animals, clothing, credit cards etc which tell nearby equipment about you, to GPS tracking units which receive GPS satellite signals and derive location information which may be read out via mobile phone call or even by direct satellite link. Trucks, ships and aircraft have similar location and ID reporting systems. Detecting such devices is difficult if you can't deliberately activate them to make them transmit. I suggest you get help from a security expert.  Test and detection equipment can be expensive and require skill to use.

Best regards, Eric.