From the book of Barg:

Today the day of 38 in this paradise of a world of Odin we call Valheim, me and Morg came across a greyling that seemed to be interested in one of the silver necklaces we just dug up from an old grave.  
We tossed the necklace on the ground and it slowly approached us. After yet another necklace was tossed to the greyling it followed us back to the camp. Morg managed to train it to refill the kiln without burning itself to bad and fed it with resin. Tomorrow I will try to show it how to work the smelter. After some argument we decided to name it Stig.
Stig is not very clever but does his chores dutifully as long as he is fed regulary. 

He sometimes needs to be brought back when he gets lost or confused around the settlement.

This mod will allow you to tame and name Greylings to keep as workers around the base.
Their behaviour is configurable to a degree.

More details in the readme-file on Nexus:
https://www.nexusmods.com/valheim/mods/970