Hi,
The best way to be in police field is to go for upsc exam and become an ips officer.
In order to apply for IPS officer you must apply for CSE exam which is conducted by upsc. The exam is of three levels - preliminary , mains and interview.
The basic eligibility for the candidate to give upsc exam is he/she should have done graduation from a recognized university/college.
And for becoming a SI or constable each State releases its own vacancy list. But if you work hard and try for upsc exam then it will be much more beneficial for you as it is a grade A service and you will get a good salary and other facilities also.
Hope it helps....

Hello dear,

Hope you’re doing well.

To become a police officer,

You need to complete your class 12th in any stream.
then complete your graduation in any subject. Take part in NCC and scouts in your Undergraduate college.

To get into IPS that is indian police service you need to clear civil services exam CSE, conducted by UPSC. All this is required if you want to become a DCP, etc. you can prepare for UPSC along your

If you want to become a police constable or head constable then 10+2 and state level recruitment exam is there.

hope this helps

Please right in the comments section if you  need more details.