How to create clicking part without click detectors?

Yes you can. With the use of the mouse you can do this. The mouse has a Target property which will hold a reference to the part the mouse is hovering over, nil if no part is being hovered over.

-- Local Script

local UserInputService = game:GetService("UserInputService")
local mouse = game:GetService("Players").LocalPlayer:GetMouse()

UserInputService.InputBegan:Connect(function(input)
    if input.UserInputType == Enum.UserInputType.MouseButton1 then
        print(mouse.Target)
    end
end)

Just an example on how you would do it. I encourage you to do some research on your own next time.

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