Abstract: Systems and methods for harvesting mechanical energy in a security tag. The methods involve: applying by a tool a pushing force so as to cause a securement mechanism disposed within the security tag to deform; transferring mechanical energy to a spring sleeve when the securement mechanism deforms due to loading applied by the tool; using an energy harvester (e.g., a piezo element or a magnet/solenoid element) to harness the mechanical energy applied by the tool, where the energy harvester is at least partially coupled to the securement mechanism; and converting the mechanical energy to electrical energy. The energy harvester is disposed between the securement mechanism and an Electronic Article Surveillance (“EAS”) or Radio Frequency IDentification (“RFID”) component of the security tag.