Capacitance measurement of active circuit

Hi all,

I am planning to measure capacitance (low cap , <10pF) of active circuit (eg. pin of microcontroler) .

If i simply use LRC meter i will reach some limitations of it because this instrument cannot measure capacitance if the circuit is active. I don't know what happen with the bridge inside or why it is not possible this kind of measurement.

Is anyone who knows how this works? i search over the internet and no model of lrc meter manual explained this.

Thanks in advance.