When you create new task sequence, there is no choice to create "capture only" TS.
But you can achieve this by splitting Build & Capture OSD task sequence to two pieces
If you are using the default build and capture TS you could try the following:
1. Just create a new empty custom TS for example "Capture" and if you like rename your old B&C TS to "Build"
2. Open both task sequences side by side
3. Cut out the group folder "Capture the Reference Machine" from "Build" and paste it into "Capture"
4. Copy! the step "Restart in Windows PE" in your "Build" TS and paste it into the new "Captute" TS at the beginning
5. Make sure that both task sequences are advertised to the Collection holding your target machine
In theory you should now be able to run "Build" first and when it is finished you just need to make your adjustments.
After that you should be able to launch "Capture" either from the "Run Advertised Programs" or via PXE and selecting it at the beginning to finish the job.