How to repair small depression in a wall?
That looks like you compressed the Sheetrock a bit , these are really hard to hide. What I have done is use a backpack sprayer with water and a squirt of jet dry (the stuff for dishwashers) wet the area down , put down some plastic and use a putty knife to scrape the area. Note if your home is older than 1985 that material may have asbestos in it. (Most of the time I will take the entire ceiling off , patch the depression and reshoot the ceiling with an orange peal or large splatter texture.
If you just clear a small area and fill it there are some can textures that I have had ok luck with but I can see the difference after painting, some may not notice.
Wetting the texture with the jet dry helps it to become wet and it scrapes right off.
Then I roll up the plastic and put it in a bag then into the trash. (With asbestos This is legal in my location if going to the dump not a transfer station).
If trying a small area after filling the hole start spraying in the center and go slow as you hit the point where you did not scrape quickly fan out this leave a heavy texture in the center but blends with the outside. You may have to wait a few minutes but try to do it with at least 8 strokes , north, south, east, west , for the first 4 then in between for the next 4. This has worked but looked best when I pulled all the old stuff down and gave it a quick orange peal texture.