[noun] + に慣れる
[verb (dictionary form)] + のに慣れる
Note: 慣れる is a る-verb (v1); conjugates as 慣れている (state), 慣れた (past), 慣れていない (not used to), etc.
The structure に慣れる is used to express getting used to or being accustomed to something. The particle に marks the thing one becomes accustomed to, and なれる慣れる (なれる) is a る-verb meaning "to become accustomed."
Attach になれる慣れる directly to a noun to express getting used to that thing.
When expressing getting used to doing something, use the Verb[dictionary form] + のに慣れる pattern. The の nominalizes the verb, turning it into a noun phrase.
Since 慣れる describes a change of state, 慣れている expresses the resulting state of already being used to something, while 慣れた emphasizes the moment of becoming accustomed.
To say you are not yet used to something, use に慣れていない or にまだ慣れていない.
A common mistake is confusing 慣れる (the process of getting used to) with 慣れている (the state of being used to). When someone asks if you are used to something, 慣れている is typically more natural than 慣れた.