Legal Question in Immigration Law in California

If you are currently outside the United States and are no longer working for the company who petitioned you for the H-1B visa that was approved, then you technically cannot legally enter (and therefore should not enter) the U.S. on the H-1B visa in your passport, assuming the validity date is unexpired.

However, the new, prospective employer can file an I-129 petition for you as a "change of employer" & you can request the "remainder" of time left on your approved I-129 petition, assuming there is any. Then you could get the new H-1B visa issued at the U.S. Consulate, at which point you would be legally able to enter in H-1B status, as an employee of the 2nd company.

The new company hopefully has an immigration attorney to file the I-129 petition on its behalf, which means this information would come to light anyway.