How do you find if a player is close to a part?

So if a player is close to a part(microphone) then It should show a message on what that player has typed, but I have no idea how to find out if the player is close to the mic. If you know what i mean xd

local mic = workspace.AnnouncerTable.MIC.Main

game.Players.PlayerAdded:Connect(function(plr)
	plr.Chatted:Connect(function(m)
	if plr.Character.Head.Poisition == math.random(mic.Position<3) then
		local screengui = Instance.new("ScreenGui")
		local textlabel = Instance.new("TextLabel")
		textlabel.Size = UDim2.new(1,0,1,0)
		textlabel.Text = m:lower()
		textlabel.BackgroundTransparency = 1
		textlabel.TextScaled = true
		end
	end)
end)

Its line 5 I just tried giving it a go