Answer :
Ich liebe dich Jakob would be the most formal/powerful way to write it.
For reference:
Ich = I
Liebe = Love
Dich = You
Jakob = Jacob
For reference:
Ich = I
Liebe = Love
Dich = You
Jakob = Jacob
Ich liebe dich jacob OR jacob, Ich liebe dich. Ich liebe dich means I love you and then the name stays the same bc its a name. This sentence is one of the few that's structured exactly like the English sentence so it's up to you where you put the name.