You cannot do so. Because has himself changed the state of browser. Let me tell you, a user would never do that. Only if he is a developer or a hacker; cracker if in negative sense. Then he would try to play around with developer tools.
My younger brother doesn't even know that he can change IE document mode from Edge (
latest version, not the new browser Edge) to IE 8 or 7 or 6. My father don't even know there is such a feature; developer tools. My grandfather doesn't even know if there is an IE. So, it depends on the users.
If he wants to open a document in IE 8 mode, he can. You cannot change that. Because browser doesn't tell website whether user is changing the document mode, or whether it is the actual browser with 8th version (of IE). Also, what makes you so sure that user, if still in IE 11, cannot remove jQuery itself? Or what if he doesn't even allow your website to send a request to download the library. There are many things.
Also, read the first comment to your question: Make designs to your website in order to provide a same functionality. Or simply, tell the user to use IE 11;
worst UX technique. To handle browsers that do not support a feature, you should try using
Modernizr[
^].