the second one is correct, its a grammar rule, you cannot use "he" as a pronoun in this way. You have also wrong spelling for "informe". It should be without "e".

'We will contact and inform him.' First of all, you misspelled the 'inform' it shouldn't have an -e. Then you should use 'him' rather than 'he' because 'him' is the most appropriate pronoun to use as an object in your sentence. 'He' is used as the subject of the sentence,