There are a lot of options here. As for a mic the most popular options I’ve seen and used are the MiniDSP UMIK-1 and the Dayton Audio mics available on Parts Express.
What are you using for your digital playback chain? Are you using a laptop/computer direct into a DAC or preamp? If so you can use REW (Room EQ Wizard) which is free or Dirac Live. If you have a streamer/server you can look into a number of DSP solutions with room correction, like MiniDSP.
If you can list the components in your system you will get better guidance to the quality of the DSP solutions that will best match it.