Obtain hidden information from blocks


I am using GNURadio and I would like to obtain different pieces of information that blocks have. For example, the “PLL Carrier Tracking” is a block that will center on the carrier frequency. In GRC I cannot obtain this found carrier frequency from the block, that is why I am asking how I could obtain this one. Do I have to change the python code of this block? How could I do that?

Thank you,