This is how i have done it, but for this to work, you would need pNotify 
vRP → Client → Police.lua:
RegisterNetEvent("cuff")
AddEventHandler("cuff", function()
if not tvRP.isInComa() and not tvRP.isHandcuffed() then
if IsPedInAnyVehicle(PlayerPedId(), true) then
TriggerEvent("pNotify:SendNotification",{text = "",type = "error",timeout = (5000),layout = "centerLeft",queue = "global",animation = {open = "gta_effects_fade_in", close = "gta_effects_fade_out"}})
else
TriggerServerEvent('handcuff:cuffHim')
end
end
end)
vRP → Modules → Police.lua:
RegisterServerEvent('handcuff:checkjob')
AddEventHandler('handcuff:checkjob', function()
local source = source
local user_id = vRP.getUserId(source)
if vRP.hasPermission(user_id,"police.handcuff") then
TriggerClientEvent('cuff', source)
end
end)
RegisterServerEvent('handcuff:cuffHim')
AddEventHandler('handcuff:cuffHim', function()
local source = source
local user_id = vRP.getUserId({source})
vRPclient.getNearestPlayer(source,{1.5},function(cplayer)
if cplayer ~= nil then
vRPclient.toggleHandcuff(cplayer,{})
vRPclient.isHandcuffed(cplayer,{}, function(handcuffed)
if handcuffed then
TriggerClientEvent("pNotify:SendNotification", source,{text = {""}, type = "info", queue = "global", timeout = 3000, layout = "centerLeft",animation = {open = "gta_effects_fade_in", close = "gta_effects_fade_out"}
else
TriggerClientEvent("pNotify:SendNotification", source,{text = {""}, type = "info", queue = "global", timeout = 3000, layout = "centerLeft",animation = {open = "gta_effects_fade_in", close = "gta_effects_fade_out"}
end
end)
else
TriggerClientEvent("pNotify:SendNotification", source,{text = {lang.common.no_player_near()}, type = "error", queue = "global", timeout = 4000, layout = "centerLeft",animation = {open = "gta_effects_fade_in", close = "gta_effects_fade_out"}})
end
end)
end)