Edgar-rft posted a Peak Finder plug-in which is available on the Audacity wiki:
http://wiki.audacityteam.org/wiki/Nyquist_Analyze_Plug-ins#Peak_Finder_rft
(late post because I’ve just updated it to fix a minor bug)
I have also updated one of my old Peak Finder plug-ins and posted it here: https://forum.audacityteam.org/t/peak-finder/34443/1