Apple has an architecture license from ARM, so they're allowed to create their own ARM-compatible cores. They do not license any core designs from ARM (like the Cortex A57), they design those in house instead.

Apple uses the Arm Aarch64 instruction set with Apple silicon which is Arm IP. I don't believe that any Apple silicon uses any other Arm IP but who really knows since it is likely Apple would have written any contracts to prevent disclosure.