If you thought that most of the "spam" you get on your website contact forms is coming from some bored pimply-faced adolescent with nothing better to do, well, that's not the case.
The spammers use a computer program to scour the Internet and find forms, ideally ones that that can be computer-completed with a set of answers to the likely questions.
A typical case: Unscrupulous "search engine consultants" (or whatever name they may be using) offer to get a lot of visits to a website for a price. If even a tiny percentage of a huge number of these result in "clicks", the "consultant" has delivered a surge in website visits. (The fact that none of these "leads" are likely to be potential customers is not part of the sales pitch from the "consultant", of course.)
To deal with this, for years, websites have employed various tools on their contact forms to try and keep down the spam submissions. These
tools are known generically as "CAPTCHA" tools, and are generally easy for humans to handle, but difficult for malicious spamming software.
One of the most popular such tools came from Google, and it has been widely used.
But Google has announced that this version of their anti-spam tool is going away, and will not work after March 31, 2018.
You should check the "contact me" or any other forms on your website for the now-obsolete version, which will look something like the image shown on the right (but can be in different colors).
Chances are, you have already seen the replacement for the that tool on websites you have visited:
In most cases it's even simpler for people, and is more effective than the one being discontinued.
If you have the obsolete version (shown at the top) on your website forms, contact your website developer right away, and get it updated.