I will use the tool called recordMyDesktop. Install it along with volume controller app:
#sudo apt-get install recordmydesktop gtk-recordmydesktop pavucontrol
Now run recordMyDesktop and start recording.
Also run pavucontrol, go to Recording tab, click the button and choose “Monitor of …” (as shown above).
You can switch it back to “Internal Audio Analog Stereo” or whatever it was to record your microphone’s input during recording..
Simple!

Check it out:DIY is the way