How is someone else controlling my iCloud account

See - > If you think your Apple ID has been compromised

If you think your Apple ID has been compromised - Apple Support

To keep your Apple ID account secure, see the following Apple articles:  

Recognize and avoid phishing messages, phony support calls, and other scams

Recognize and avoid phishing messages, phony support calls, and other scams - Apple Support

See who has access to your device or accounts

See who has access to your iPhone or iPad – Apple Support (UK)

Delete suspicious content from your devices

Delete suspicious content from your devices – Apple Support (UK)

Check your Apple ID device list to see where you're signed in

Check your Apple ID device list to find where you're signed in - Apple Support

• if you see devices that don't belong to you, delete from your account.

Personal Safety User Guide -> Personal Safety User Guide – Apple Support (UK)

Manage and use your Apple ID -> Manage and use your Apple ID – Apple Support (UK)

(if you haven't already done this) Two-factor authentication for Apple ID -> Two-factor authentication for Apple ID - Apple Support

Change your Apple ID password -> Change your Apple ID password - Apple Support

• Create a strong password for your Apple ID, It is best if your password consists of eight or more characters and include upper and lowercase letters, and at least one number. You can also add extra characters and punctuation marks to make your password even stronger. 
• Never provide your password, passcode, security questions, verification codes, recovery key or any other account security details to anyone else. Apple will never ask you for this information.

Then see this Apple article: What to do after you change your Apple ID or password

What to do after you change your Apple ID or password - Apple Support

👉 Never jailbroken your iPhone.

NeedhelpMS Said:

"How can I find out who is hacking & controlling my phone ?"

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Secure your Info:

Being so concerned, you should secure your info. You should then (A)Verify your devices, and (B)Modify your credentials. I'd say it would be wise to open a new eMail address and use that for your Apple ID.

1. Verify your Devices:

Verify that all devices are logged in to your account, by using this link: Check your Apple ID Device List to See where you're Signed in - Apple Support

then...

2. Modify your Credentials:

Having been stollen, someone lily has your credentials. So, by all means, modifying them.

• Modify: your login credentials (Using Both a New eMail and a New Password for each and all sites)
• Associate: a different method of payment to your account
• Enable: Two-Factor Authentication for Apple ID and for all other accounts that have such an applicable option

Apparently, it is against the rules of this community to “speculate” or provide an answer that is “speculative”, so I can not give you an honest answer. I do know when they start deleting your truthful comments, and you know them to be true, then you are definitively onto something they don’t want anyone else to know!

Of course, that’s speculation! So, delete that too!