MacBooks, and Macs in general, have only one headphone jack. You can connect a headphone/mic combo device to it, and it will work just fine. You can also use an external device though it will normally still be detected as a combo device. If you want to use an external mic with a MacBook, it’s fairly easy to do so. You only need to make one small change.
External mic with MacBook
Boot your Mac and connect your mic to the headphone jack. Mics come in different configurations; some do not need to be powered separately, while others have their own power source. Still others may have an on/off button, while it may be absent on a general desktop mic. It is up to you to determine how the mic is put in its ‘working’ state.
Once you know it’s On, you need to set it as the input device. There are two ways to do this.
Input device – Menu bar
To set the input device from the Menu bar, hold down the Option key and click the speaker icon in the menu bar. The menu will have a ‘Input Device’ section and under it, your external mic will be listed. It is possible that if you’re using a name brand mic e.g., a Yeit microphone, it shows up with its own name/model number. If it’s a generic mic, or a low end one, it will likely just show up as ‘External Microphone’. Select it and you can use your external mic to record.
Input device – System Preferences
Open System Preferences and go to the Sound preference. It’s divided into several tabs. Go to the Input tab and your input devices will be listed there. Your external mic should show up there as well. It may show up with its brand and/or model name, or it may just show up as a generic mic. Select it and it will be used as the input device. You can now record from it.
When you connect an external mic to a MacBook via the headphone jack, it normally expects the device to be able to handle both audio input and output. It can switch to just using it as an input device which is what happens when you select the mic. What all this means is that while you have an external mic connected to the MacBook, you will not be able to output sound to your speakers. If you go to the output tab, you won’t be able to select your MacBook’s speakers.