First, if you're asking about "proof" for such an obvious statement, then again, your'e not very bright. Again, not an insult, just logic and common knowledge. It's not something you can "quanitfy", but if you actually take your time and research, you'd find the direct correlation.
https://lmgtfy.com/?q=correlation+between+low+intellect+and+trump+supporter
Go ahead and see what you can find. If you believe it's the opposite, then it's clear you're not very intelligent.
For example, you look at many northern states (Where people tend to be more educated - again, more schooling, more industrialized environment in the north, where there's far more importance on schooling, which is a FACT), those states tend to hold a much higher priority on education, whereas, in the south, in America, less people study at university, less people go to university, less people are educated. Again, this isn't an "opinion", it's an actual fact, backed by studies, that northern states and the people from northern states, have a far higher affinity for knowledge and education - and those states tend to vote more-so, against Donald Trump. That alone should show the inclination of those educated, voting more against Trump, whereas, you find more southern states are dominated by republicans (many of which are gun nuts who use their bias, and lack of intellect to justify their support for Trump - again, not all, but there's certainly a trend).
I'd like you to actually do some research into the subject, so that you can actually understand from an intelligent and factual point of view, as opposed to a, "this is my bias, herp, so I'm closing my ears, shouting 'la la la'" stand-point. Thanks.