how scrum master know dev estimate right because only dev know all tech to do this task?

how scrum master know dev estimate right because only dev know all tech to do this task?

Each Sprint, is the Sprint Goal being met and is at least one Done and immediately usable Increment being created?

What does it mean to estimate right? And why is that important to know? Estimates are approximations that can vary in accuracy. If you for instance are making estimates on the time or cost of getting a task done you will be able to know how accurate the estimate was only after you are done with the task, and by that time the accuracy of the estimate of that task is likely not that important anymore.

Yes, my team alsway Done and immediately usable Increment being created, but i want push their performance, I think they can do more now, to optimize human resources for company costs 

That doesn't sound like trusting a self organizing team, nor prioritizing value. 



Do not to those things. Read the Scrum guide again and think about the role of a Scrum Master. 

Yes, my team alsway Done and immediately usable Increment being created, but i want push their performance, I think they can do more now, to optimize human resources for company costs 

https://read.gov/aesop/091.html