Does Google checks your search history or emails before hiring you?

Probably not, but you should always assume that if they have the capability (and they do) that they will do the least intrusive thing they possibly can (it can't be the most intrusive thing because of a public relations nightmare scenario also because that would raise their risk too) to minimize their risk. I'm talking about a system that gives some sort of score to a candidate based on whatever Google can find on- and off-line about that person (off-line through their partnerships... for example banks, social networks, internet service providers, etc.) I am only speculating but I wouldn't be surprised if they did something like that in certain markets. Anyways, always assume the worst when it comes to Big Tech. Data is the New Oil as they say.

I don't think recruiters have access to such a stuff.

If they did, that would be huge issue imo.

But I'm only guessing, not a Googler, so.

I assume they do use your search history for some purposes. For instance I have been enrolled inside the Foo Bar challenge from Google, and from my deductions it is thanks to my search history (mainly programming-related). The Foo Bar challenge is a suite of tricky programming questions and in the end, some of the winners of the challenge receive a message from Google's recruiting team (as I did) where it can lead to a job at Google.

This is only my deductions from my experiences with Foo Bar, it might only be in that case, I am not exactly sure, but you should assume they do.