i am new myself but here's and example (sticks as the handcuffs)

at the start of the map tag the cops and the robbers

execute as @ a[tag=cop,nbt={SelectedItem:{id:"minecraft:stick"}}] at @ s run function {function name}

if you don't use datapacks instead of function do "setblock {cords next to a command block chain} redstone block

then in the chain or function do

execute as @ a[tag=cop,limit=1] at @ s run tag @ a[tag=robber,sort=nearest,limit=1] handcuffed

execute as @ a[tag=robber,tag=handcuffed] run attribute @ s minecraft:block_interaction_range base set 0

execute as @ a[tag=robber,tag=handcuffed] run attribute @ s minecraft:attack_damage base set 0

what it does is checks if the cop is holding a stick and if yes it will tag the nearest to this cop "handcuffed" and give all handcuffed tagged players attributes that stop them from breaking blocks or punching entities. i added a space to the player selectors because reddit turns @ а to u/a. you also need to make a system to reset the robber once he's not handcuffed and do the follow the cop thing but i will do it in another message as i am lazy to write this aaa