Hello there, @drgochis ...
There are third-party applications such as the Respondus Lockdown Browser or Honorlock that can be purchased which integrate with Canvas to make quizzes more secure and prevent things like screen capturing and copy/paste. (There may be others available on the EduAppCenter website.) But, it may still be possible for your students to take pictures of their screen using their smartphone. So, you'd want to keep those things in mind, too.
Also, my friend @kona has a blog post here in the Community called Quiz Settings to Maximize Security - Canvas Community which you might want to read through...as it may have some helpful tips for you as you design your quizzes in Canvas.
Sing out if you have any other questions about this...thanks! Take care...be well.