Unusual sounds during calls, such as clicking, static, or distant voices, may indicate phone tapping.
Decreased battery capacity and increased usage can be a result of your phone transmitting data to a third party.
If your phone shows activity when not in use, it might be a sign of surveillance.
A phone taking a long time to shut down, especially after calls, texts, or browsing, could be sending data to a third party.
A warm battery temperature when the phone is idle could suggest ongoing secret data transmission.
Unusual or coded texts may indicate the presence of spy software on your device.
Keep an eye on increased data usage, as some spy apps use extra data to send collected information without your knowledge.