How to stop my little sister from snooping in my room when I’m not home?

Today I came home and went in my room, noticed that my paint was left out on my desk which I know I always keep my desk cleaned.
I yelled about my sister and my mom made her spit out the truth bc she was lying at first. She admitted it but was smiling about it like it was so funny.
It’s genuinely a thing I don’t trust her to be around with since it has happened more than thrice.
Even worse was that I noticed she left some paint stains on an object, so it adds on evidence for me.
I understand about trying to set a trap or maybe hide my things better but isn’t it human decency to not snoop around others stuff and respect their privacy?
Just bc she’s little, doesn’t mean it’s an excuse. She’s old enough to understand yes and nos and simple privacy.
She’s high elementary grade age fyi
She does this to not only me but to all of my sisters whom are older than her and younger than me (I’m the eldest)
My parents just yell at her than make her face the consequences, literally it doesn’t teach her anything nor stop her from doing what she’s doing.