Shifting to another job with in one year

1) If the visa has not been cancelled, you can travel on it
2) For less than one year, you CANNOT get mobility without consent/approval from your past employer.  The only way you can get another visa is for your employer to cancel your previous visa and another employer to sponsor new one for you
3) You didn't have to pay them anything as per labor law.  But anyway, it is done now

I was working there as project engineer and i think they will not give mobility. What to do in such case, exists any way out?
Secondly, if they cancel my visa would i be able to apply for another job while staying in bahrain as i am from Pakistan and i heard there's ban for new visa these days.
Kindly guide the best way out of this situation.

As I said, if you worked less than one year with an employer, you will NOT get mobility unless the employer agrees.

Only other way is to cancel visa, stay in Bahrain and get a new employer to sponsor a new visa (within 30 days from visa cancellation - after which you must leave).  That can be done without leaving Bahrain.  But yes, there is a big problem for new visas for Pakistani's right now.

There is no best way out of the situation - I have listed your only options above.

Thanks brother.
Soem more advise required.
1. Like if i travel back on same visa, will company be notified of my arrival?
2. Can they cancel visa if i even stay in bahrain without my passport?
3. If with pakistani passport i stay in bahrain, it would be easy to apply for new visa while staying there?
Thanks!

1) No.  But if they log into the EMS system, they can see whether you are in the country or not
2) Yes of course.  Passport is not needed to cancel visa.  It can be cancelled in the EMS system online within 5 minutes
3) No one can say.  New visas are being routinely rejected even for children born to parents who are living in Bahrain and some are being granted for people who are outside Bahrain so it seems hit and miss

As per point 2 above, I would advise you to check your visa status on lmra.bh as you seem to be thinking that passport is needed for cancellation.  Your employer may already have cancelled your visa.

Lmra.bh still shows valid employment visa.