Hello Nitish,

To become a police inspector you have to go through your high school , intermediate and graduation too. After graduation you need to clear CGL exam through which you will get a selection for SI post and further you get permotion based on your performance. 

Now coming to your second question daroga is a lower rank post whereas inspector is a high rank post in police department. 

Hope it helps. 

Thank you :)

Now coming to your second question