discuss How to catch pending delete domain after drop using bot ?

You could but it's not the most effective.
Usually people use dropcatching services for that.
Check out the correct section of nP about it https://www.namepros.com/forums/domain-expiration-and-domain-drop-catching.13/

Ok thank you . But drop catching is not very cheap .

Which drop catching service is the best ?

I strongly recommend you to practice with hand registration before go to a pricy service. Your picking skills are more important than anything else.