I wonder why some people keep bugging into my iPhone

As long as your device is not jailbroken and you have not given out you passcode or Apple ID password, then it is not possible for someone to be bugging your phone.

• Check your trusted devices and remove the ones you do not have or want access to.

Manage two-factor authentication for your Apple ID from iPhone - Apple Support

• Change your Apple ID Password

Change your Apple ID password - Apple Support

• Change your Passcode

Set a passcode on iPhone - Apple Support

• Review support article on what to do if you think your Apple ID has been compromised.

If you think your Apple ID has been compromised - Apple Support

After doing this, more information can be given if you give specific examples of problems you are having.