If someone else has remote access to your iPhone, the window to fix it is short and the steps are specific. Work through this list in order; it takes about twenty minutes.
- Change the Apple Account password from a different device — appleid.apple.com, then review the Devices list and remove anything you do not recognize. Do this from a computer, not from the phone you suspect.
- Review trusted phone numbers — Sign-In & Security > Trusted Phone Numbers. An added number you do not own is how an attacker receives your 2FA codes and keeps access after a password change.
- Check for configuration profiles and MDM — Settings > General > VPN & Device Management. A profile or management enrollment you did not install is the strongest sign of remote supervision. Remove it (this may require the device passcode).
- Audit Screen Time — a Screen Time passcode you never set, or restrictions you did not create, means someone has administrative access to the device.
- Run Safety Check — Settings > Privacy & Security > Safety Check > Reset All. It revokes location, camera, microphone and account access granted to third parties in one pass.
- Update iOS — most remote-access chains rely on an unpatched Safari/WebKit or a profile installed via a link. The current iOS release closes the known ones.
- If the phone is fully compromised — back up what you need, erase it, and set it up as new. Restoring the same backup can bring the profile back with it.
What does not exist is a tool that lets you do this to someone else's iPhone remotely. Apple's security model is built specifically to prevent it, which is why the "remote iPhone hack" services you see advertised either want your Apple Account credentials or install nothing at all.
For a supervised child's iPhone, the supported version is Family Sharing plus Screen Time — visible to the child, administered by you. Ultimate Phone Spy takes the same transparent approach on Android, Windows and Mac, where device-level access is permitted (parental control features).