2008 Ford Taurus clicking noise from the dashboard

When I start my car (and sometimes when on the highway) a clicking noise (like tapping on wood with a pen) sometimes start right after the engine is on and actually I heard it few times when the key is just one click before the engine starts)
it has nothing to do with AC/heat since I hear it while ventilation is off. The car starts normally without any problems with performance/gas use.
No lights are on in the dashboard.

I should have specified where exactly the noise is. It comes from right behind the speedometer. Nothing comes from the engine. I looked today behind/under the steering wheel. I could saw a black piece of plastic that shakes while the noise is on, then once the noise is gone it stops shaking. It has few electric wires going into it. I do not know what it is function (looks attached to the back of the speedometer)

I hope this is clear.

if you need to ask any further questions, please feel free
Thank you.