There two easy ways to download youtube videos subtitles
First. Open the video in PC or Laptop, from which subtitles you want to download, on vidoe page, upon little scroll download, you'll see a save option, click it. Then it will show, open script, click it, it will show all the subtitle of that video which you can drag and copy by highlighting it.
Open the video you want to download its subtitle.
Before the video url add subtitle.to/ like this
It will redirect to submenow.com there you can click the language in which you want to download subtitles