How to display the frequency of a cosine wave?

Hi, I want to display the frequency of the wave, I just know the
FFT_sink, and it does show the frequency on the screen, I want to get it
as series like this: 1103Hz, 986Hz, 546Hz and so on.
For example, in the grc file, I place a Signal Source which produce
a 1K cosine wave with a sample rate of 32k, now I want the terminal to
output 1K or the windows to output 1K, how should I do?
I tried but found nothing.
Thanks and regards.

    Qin J.