I replaced the rear rotor and caliper and it still squeak?

Hello,

Have you replaced the pads along with the rotor and caliper?
If you are reusing the pads, it is likely the reason for the squeak.
Any time installing new pads, you want to make sure that the anti-rattle clips the installed properly. Also keep in mind it is a good idea to use anti squeaking compound to the back of the pad. That can reduce squeaks.

Here are couple of helpful articles:

https://www.2carpros.com/articles/how-to-replace-rear-brake-pads-and-rotors
https://www.2carpros.com/articles/brake-caliper-replacement

I have attached the rear caliper procedure for your reference. It has the parking brake instructions.

Please let me know of any questions.
Thank you.