How can I get my baby to sleep through the night?

I am a single mother to a 6 week old little boy.
He sleeps alot still obviously but during the day he sleeps so perfect and uninterrupted, a freight train could come through the living room and he wouldn’t flinch but last week i had to return to work since im the only one supporting my new little one and i also have an 8 year old son too. The little bit of time i did get to have off for maternity leave i would nap when he napped during the day while my oldest was in school but now being back at work during the day and having to be up early to get the oldest to school my day time naps are over and by the time i get off and get the oldest to bed the baby is waking up to party all night. He will doze off and sleep on me or in my arms but the second i put him down he wakes up instantly and takes so long to fall back asleep. During the day he will sleep anywhere whether its the crib, bassinet it dont matter but at night he wont sleep anywhere when i lay him down so i can get some much much needed sleep and he will pass out in my arms but i cant sleep that way its not safe and if i put him down he instantly wakes up and if i do succeed in laying him down the sound of a feather dropping will wake him right back up. Im so tired.

Any tips on helping him sleep better at night or products i can buy to help soothe him at night to sleep better? Momma is very tired😩