Meaning: to mark with a tick mark, to mark something as done
Examples:
I like my “to do” list to be clear. Please wait while I check off these last two things.
Here is a list, let’s check off the names of the people we don’t want at the party.
To get out
Meaning: to become known, to become public knowledge Examples: I don't want it to get out that I am leaving. Please don't tell anyone. If this bad news gets out, people will panic and try to run away.