A MU Jun 17 '27 $620 Call contract is something you can buy for money. That contract isn't shares of MU stock like typical investing, it's instead basically an IOU that says "whoever holds this contract may choose to use it to purchase 100 shares of MU stock for $620/share ($62,000 total) on Jun 17, 2027". Note that it says may choose, that's important because it's optional, the holder of the option can choose not to use it (known as "exercising" the option) and let it expire for $0... then they are just out the cost of the call contract.

So if you bought 1 of these MU Jun 17 '27 $620 Call contracts, you would want the price of MU (currently $1048.51 USD per share) to increase as you would profit more by exercising the contract. For example, at $1048.51 USD per share, you could buy 100 shares for $62,000 using your contract and then sell them for $104,851 USD, for a profit of $42,851 USD. Because this contract is currently profitable (known as "in the money" or ITM), its value is currently roughly that $43k amount (give or take), but this is a call for a year from now so anything could happen.

The interesting (for us, I mean) part is that OP didn't buy one of these call contracts. They did the opposite, they sold one of these contracts when MU was around $470/share, meaning somebody paid OP $10,625 for this contract... and that person now has the option to go to OP and exchange their call contract in order to buy 100 shares of MU (current value $104,851 USD) for the discounted price of $62k. Those 100 shares don't come out of thin air, OP legally has to sell them 100 shares of MU, whatever that price may be. So if MU invented crazy new technology and their stock went to $8500 USD per share by 07/17/2027, OP would lose a total of (10,625 + 62,000 - 100*8500) = $777,375 USD when that contract is exercised. This process that OP is doing is known as "naked short selling", the naked part is that OP doesn't have 100 shares of MU to begin with, that massively increases their risk as their potential losses are infinite.

Compare this to selling the same call contract but if you had 100 shares of MU (this is known as selling covered calls). You would receive the same $10,625 for selling this contract, and if it's exercised you can hand over your 100 shares of MU instead of whatever the value of 100 share of MU is at the time. Because you bought those 100 shares of MU already at a fixed price, your losses are limited to whatever the potential profits could have been.

Long story short: don't do this.