Sorry if this has been covered a hundred times before, but I've no idea what to search.
In David Lee Roth's version of Tobacco Road, the riff contains a few well placed high-pitched squeals. What are these and how are they achieved?
How may The National D help you waste your time?
take a battery some clamps and a testicle... you can figure out the rest

oh and theyre pinch harmonics and its been done to death use the search function ****er
You need to hold the pick in a way that your thumb is gonna hit the string once the pick has hit it, typically this means showing very little of the pick to the string.

The lower frets are a bit harder to get you may need to dig in a bit more, however, once youve found them best suited ones for you then you are sorted. Remember you can hit different squeals dependant on where you hit the string, experiment!

For the Zakk Wylde/ modern Metalcore stuff it helps to tune down, maybe loosen the E down to D. I find that helps.
Those are in actual fact, not pinch harmonics. What you will find is that it's really a pig having its tail pulled and twisted by David Lee Roth, driving it into a state of rage and causing the poor beast to whine and squeal while having its face forced into a microphone, thus producing the high pitched noises that these people refer to as pinch harmonics.