I would like to apply for H1b academic for the post of assistant professor

H-IB visas are very complex. You have to know when to file - or you may be wasting the filing fee. Where to file - otherwise you will have delays. What evidence to include, otherwise your case may be rejected. There is also a difference if you have a bachelor's or master's degree from the US. There must be an employer who applies for an applicant to obtain this visa. There are special regulations about what the employer must do to qualify - can he afford to hire this person and pay the prevailing wage? There are also many limitations on the person who is being hired. For example, how long has he been in the US, what are his credentias and what other visas has this person had during the last 6 years. You definately need an immigraion attorney with experience in H-1B visas.

My colleague is correct. If a US university is extending you a job offer, the university in general takes care of the immigration issue. This is my direct experience. Talk to the university HR and be sure to check whether the institution is going to sponsor you. If not, you absolutely need to work with an immigration attorney. The process is complex and time consuming. Good luck.

If the university offers you the position, they will petition for you. The employer holds the rights to the petition and therefore it is their burden of production and proof. The foreign national beneficiary has very little input.