You can’t.
As Cipsoft explained back when they released the dummies: every “Use” action stops the training action.
Why is this? To my knowledge when you use your hands for do something, lets say to wash the dishes you need to stop that action to do something else like dry them, its the same with the training.
You are using “your hands” to train, in order to do something different with them, you will have to stop training to move things around (wich is what you do when you use your depo).
As cipsoft said:
“Your character will no longer attack the dummy when you move your character, cast a spell, move/take items or perform other "use" events.”
You can read all the info on:
https://www.tibia.com/news/?subtopic=newsarchive&id=4577
Hope this helps to clearify your doubts!