You can do this with the following apps:
Web Browser
While capturing video, you can record system audio (* only if the browser tab is selected as the capture area) and microphone audio like narration.
Related: Capture images and video and add steps (Web Browser)
https://teachme.jp/8/manuals/35657034
Mobile App
Audio is recorded along with the video during recording, so you can create videos with narration by recording while narrating.
Related: Upload video (Mobile App)
https://teachme.jp/8/manuals/7899343