Got your number
To have leverage, control, knowledge, or power over another individual.
You should be scared to death because he's got your number.
i got your number
An expression to indicate that you're keenly aware of what's *really* going on, and that you're "onto" a person's true intentions, and have direct insight into their thinking.
Down Syndrome Jason: "Hey Katie, wanna hang out after school today?"
Katie "Um...I would love to but...um...I'm really busy today. Maybe some other time. OK? Sorry, buddy. Bye."
DS Jason: But...you said that the last time I asked...I see. I got your number.
Katie "Um...I would love to but...um...I'm really busy today. Maybe some other time. OK? Sorry, buddy. Bye."
DS Jason: But...you said that the last time I asked...I see. I got your number.
i've got your number
When someone is out to get you or has it in for you!
You banged my girl when you had no business or right to so now I've got your number!