Is it Legal to Travel on B1 Visa for H1b Visa interview

I am currently in Mexico and want to apply for H1b Visa. I have been approached by few consultants who are eager to file Visa for me but are asking me to come to US for interview.

I have currently US B1 Visa.

My question is is it Legal to travel for H1b Visa interview on B1 Visa.

B-1 is not meant for that purpose, and should not be be used to give H-1 interviews. You will be asked at PoE about your purpose of travel and you are expected to reply truthfully.