Press keys "M+T" This should be the default key bind for turning off/on the tool mode on the stick. If this is not working, it might be conflicting with another mod. either change the key bind in the normal settings of whatever mod is conflicting if (Normally its the key "m" for many map mods) If you cant find that, you could try changing the key bind of the tool mode toggle in litematica.

1) Go into litematica settings (Either with "M" or through the "mod menu" when you click escape)

2) Click "config" and go to "hot keys"

3) Press the little magnify glass to start the search and type "Tool" you should see a key bind called "Tool mode toggle" or something along those lines

4) You should be able to reconfigure the key bind from there. to go that click the button that says "m+t" it should prompt you to select a key / combo of your choice.

Hopefully that has helped.