Yes, your directional scanner can pick up NPCs too.
Your directional scanner only scans what you have chosen to scan. Usually people use their dscan with a filter, because the list is too big to quickly show threats otherwise.
But if you want you can add more entities to your dscan to easily find them.
Green: Open your overview filter list to make a new one.
Blue: Create a new filter that you intend to use for dscan. I usually begin mine with 'dscan: ’ to distinguish them from overview filters, but you could use it for your overview as well. Add the NPCs you wish to find on the list.
Red: Change your dscan to filter using the new filter you just made.
I’ve used this in the past to hunt certain types of NPCs in Pochven. Pretty useful when you can make them show up on dscan!