Captchas impose an extra burden on the user. Bad captchas are extremely frustrating; good captchas are merely annoying.
It's a trade-off. If you want to encourage people to use the contact form as much as possible, then take off the captcha. This may increase the amount of spam you get.
In my experience, a simple honeypot form field is enough to prevent all spam. No need for a captcha:
Add an extra field to your form
Hide it using CSS {display: none}
For accessibility, add a label that says something like, "Please leave this field blank; otherwise your message will be rejected. This is an anti-spam measure; sorry for the inconvenience."
When handling the form, check if that field submitted anything. If it did, reject the message
It's a trade-off. If you want to encourage people to use the contact form as much as possible, then take off the captcha. This may increase the amount of spam you get.
In my experience, a simple honeypot form field is enough to prevent all spam. No need for a captcha:
Add an extra field to your form
Hide it using CSS {display: none}
For accessibility, add a label that says something like, "Please leave this field blank; otherwise your message will be rejected. This is an anti-spam measure; sorry for the inconvenience."
When handling the form, check if that field submitted anything. If it did, reject the message