|Either 1.) You're clicking a sponsored link, or 2.) Your computer is infected with malware.|
1.) The sponsored links on Google's Search Engine Result Page (SERP) are located at the very top of the results page and in the right column. Sometimes the advertisement looks exactly like the homepage of an official product/service you're looking for, but it turns out to be a different site. You can tell they're sponsored ads because they have a yellow background (light blue in Bing) and say Ad in the upper-right corner. I suggest avoiding sponsored ads and clicking the actual search result itself.
2.) You likely have malware, but I wanted to cover the bases. Download, install, and run a full system scan with Malwarebytes' Anti-malware (free). Clean up any infections it identifies. After it's done, it will produce a scan log as a text document. Please copy/paste that in your next post.
Apologies if I don't respond to your reply immediately. I don't check this site daily, but you're welcome to PM me as a reminder.