YA Fantasy about a thief, he is going through a castle as a final test. I audio book and I listened to it from between 2018 and 2022

[Joseph]

I read it around 2018-2022 Male main character sneaking through a castle as some type of test. He used grease on door hinges to make sure it would squeak and reveal him. I think he speaks about the guards with familiarity so maybe it is a mock castle? Sorry it’s so vague it’s been a few years and I only listened to a small portion with my cousin who doesn’t remember either.

[Joseph]

Sorry he used the grease to make sure it wouldn’t squeak