Can I extract audios from DVD menu instead of DVD titles?

Yes. Simply select "File - Open single DVD VOB file..." in Step 1 and browse to the DVD menu VOB file under the VIDEO_TS folder of the disc.

Usually the main menu is put in VIDEO_TS.VOB and title menus are named in VTS_??_0.VOB. Like VTS_01_0.VOB for Title 1 menu, VTS_02_0.VOB for Title 2 menu, etc.