1. Download "Soundflower" and install
The first time you run the installer (Soundflower.pkg), it will ask for your admin password, this is an information "
“Soundflower.pkg” can’t be opened because it is from an unidentified developer"
"and will FAIL!
The correct way is right-click or Control-click Soundflower.pkg, "Open", then finish install.
It should inform you installation was successfull.
2. Audio MIDI Setting
2.1 Aggregate Device
Go to "Audio MIDI Setup" which in Launchpad System Folder, click "+" create a Aggregate Device, Choose "Built-in Microphone" and Soundflower(2ch)
2.2 Multi-Deive Device
2.3 Sound-Input&Output
Open "System Preference - Sound", Select "Multi-Output Device in Output"
Select "Soundflower(2ch) in Intput".
3. Record
Open "QuickTime", "File - New Screen Record", Click Down right button on Record Button, check Mircophone with "Soundflower(2ch)", Then Start.
Then Record with System Sound also you can hear the sound with Speaker.