Randomly select values fromone column and paste them in another table in sql

I want to randomly select values from one table (1000 rows) and put them in another (4000 rows).

First table is Customer (1000 rows), second table is Customer_Account (4000 rows). They both have a column Customer_ID and Account_ID. In the Customer_Account table, only the Customer_ID column is populated. The Account_ID column of Customer_Account table I want to populate with randomly selected values from the Account_ID column of Customer. This means that the same value from the Customer table may occur multiple times in the Customer_Account table.

This query puts one randomly selected single value from the first table to another 4000 times:

set CustomerID = t2.CustomerID
from Customer_Account t1
cross apply (
    select top 10 CustomerID
    from Customer 
    where CustomerID=t1.CustomerId
    order by NewID()
) t2

Any suggestions on how I can solve this?