Mice in a house cannot be caught when you are sitting there. They will be aware of your presence, but they can be caught with a trap, even if you are not there. Satan uses traps like this. Satan does not announce himself to us as he did to Jesus. But He does, in fact, have traps laid for us and he has something to say to us, and we should have something to say to him.
Now the serpent was more crafty than any beast of the field which the Lord God had made. And he said to the woman, "Indeed, has God said, 'You shall not eat from any tree of the garden'?" (Genesis 3:1 NASB)