Someone hacked into my iCloud account

Hello,

My friend post a picture of me on Instagram and I was wondering how they got that picture. I did post the picture on snapchat a long time ago, But to my memory I don't remember anyone screenshoting the picture from my snapchat and on top of that,the that I posted on snapchat I had a comment typed on top of the picture. I dont remember if I saved the picture to my phone or not and if I did I must have deleted from my phone because I did not like it.

Is there any way for someone to hacked into my phone or my iCloud account, would it tell you if someone hacked into your account or is it possible that someone hacked into my camera