Below is steps of how to secure Apple phone from hackers and theft you can use.
It’s important for you to take every step necessary to protect your data from hackers and thieves and maybe to track your smartphone once it’s gone.
Preventing data theft and casual hacking.
Lock code, you can use a 4 digit number or longer passcode. And if you want, you can activate a feature where entering a passcode incorrectly 10 times will wipe the phone.
How to secure Apple phone from hackers and theft with using lock screen features
Lock screen features.
You can turn off Siri, with go to Settings > General > Passcode Lock. And you need to turn off access to the Control Center and Notification Center. Go to Settings > Control Center and Settings > Notification Center.
Tracking and Wiping your phone.