Look for it under the Wall Paint category.
The mod for The Sims 4 , created by user Poker on Mod The Sims (MTS), is a functional tool used to measure the height of Sims and objects in the game world. Key Features of the Mod Height Chart by Poker at Mod The Sims 4
Download the file from the official Mod The Sims page and place it in your Documents/Electronic Arts/The Sims 4/Mods folder. Look for it under the Wall Paint category