It's really simple. You grab the child by the arm, just enough to hurt a bit, pull them close enough to whisper in their ear "You will stop NOW."
I must note that this only works if you have used the opportunity of all the preceding years of their life to instill in them the appropriate amount of terror at the prospect of their imminent punishment.
We used to call all that prep work "parenting".
"... And it was three goddam years ago. The little f**ker had thrown all my papers all over the floor. All I tried to do was to pull him up. A momentary loss of muscular coordination. I mean... A few extra foot pounds of energy, per second... per second...."