"Can anyone help me with this"

I guess not.

Plenty of replies have already come in asking you to specify the derivative as each one depending on its Vcc levels (3.3V to 5V plus) will have a differnt voltage to see it as high.

Then there are issues like the particular configuration of the pin. Even in the same MCU all port pins are not created equal. If you don't know what you are doing and connect Vcc directly to a port pin (to make it high ) , in all probability you can end up with a fried MCU.

And you said you wanted to connect a toy mobile to the MCU - now how about the power supply for the toy mobile and that for the MCU ? What levels are they ? Do they share a common ground ?

So, to sum it up, your problem is not only the High level defenition. Much more needs to be known if anyone can even attempt helping you.

Raghu