say I want something from someone and I promise to give him something in return when I actually don't have it, what's the appropriate verb to use in that case?
While saying something that isn't true is to lie, in your case you are asking for something more specific.
4 : to cause to accept as true or valid what is false or invalid · deceiving customers about the condition of the cars · bluffing at poker in order to deceive the other players
: to make someone believe something that is not true : to practice deceit; also : to give a false impression · appearances can deceive
Her parents punished her for trying to deceive them.
He was accused of deceiving the customer about the condition of the car.
Here, the lie is part of a greater deception so that you can get something you want.
"A promise that is devoid of worth or meaning, one that cannot or was never intended to be carried out. John may be a sweet-talker, but in reality, he's a lowlife full of empty promises."
a damned liar TFD
One that tells lies.
mislead could be another answer. Perhaps the OP is too vague.
Cause (someone) to have a wrong idea or impression.
‘the government misled the public about the road's environmental impact’
To compare possibilities of "making a promise unlikely to be fulfilled" (title) to "something from someone" (first line of OP) the details of the situation would contribute to which word would be fair to apply.
Example: Let's say Elon Musk promised a delivery date to customers and investors that was ... say ... very optimistic.
How much doubt he had might be the difference whether this promise were a 'lie' or not and how badly he thought he might be off and how much he thought it would ultimately hurt the other (would he never meet the promise or just miss the date) might determine the difference between a con, being misleading, deceiving or other answers given here.
Some might even step shorter and use a word closer to "sugar coated" or "promised the moon" or something that leaves some doubt while still suggesting some level of misleading.
The exact same act might fit ALL of the words, but Different choices from different perspectives of the facts.