ReCapcha Number Generator Laravel 5.5

I want to Display a ReCapcha number image in Contact Form While submitting the form user must write the recapcha code in given field...I need to know that how can i generate these randon numbers...

Here is html for input field and img..

 <img src="" alt="This Is a CAPTCHA Image"><br>
 Enter the text of the image above <br>
<input name="strCaptcha" type="text" size="8" value="" maxlength="8">

Below Picture is an example for recapcha.Please review and tell me how i can do this..

via Chebli Mohamed