Imagine a camera that could see everywhere at once, in every room, every backyard, every corner of the world, all at the same time. Sounds impossible, right? But God really is like that: He has super-vision and sees everything, everywhere!
But don't worry, it's not so He can catch you doing something wrong. It's because He cares about you so much that He never, ever loses sight of you. It's like a mom watching her child swim in a pool: she's not spying to punish, she's watching because she loves and wants to keep him safe.
There's a story in the Bible about a man named Nathanael. Before anyone even introduced him to Jesus, Jesus already knew who he was and had already seen him sitting under a fig tree, all alone! Nathanael was amazed that Jesus knew him without anyone telling Him.
God sees the good things you do that nobody else notices. He sees when you're sad, even if you hide it with a smile. He sees the hard right choice you made when it would've been so much easier to choose wrong.