Using the Multileader or Dimensions in AutoCAD, you can create a custom arrowhead and use that instead of the default ones that ship with the software. When setting up a style in Civil 3D, you are stuck with the default ones, there's no option for using a custom one.
There is a trick, however. If there's an arrowhead that you know you will never use, simply edit that block!
In the following image, I set the arrowhead for my General Note label to use the Architectural Tick arrowhead but I had already edited it and added in a few circles.
The block that I edited was called, "_ArchTick".
One thing to note (and I just found this out as I was writing up this blog post), the block won't be available to edit until at least one label style is using the arrowhead.
Pretty cool stuff! I love learning new things!