Let's solve the problem step by step.

1. The given 4-digit number is 6561.

2. To find the highest value, we rearrange the digits in descending order:

   • Rearranging the digits of 6561 in descending order gives 6651.

3. To find the lowest value, we rearrange the digits in ascending order:

   • Rearranging the digits of 6561 in ascending order gives 1566.

4. Now, subtract the lowest value from the highest value: $6651 - 1566 = 5085$

So, the result is 5085.

Would you like more details or have any further questions?

Here are 5 related questions to explore:

1. What if you used another 4-digit number, like 4321, and followed the same process?
2. How would this process work for a 5-digit number?
3. Can you form a general rule for finding the result for any 4-digit number?
4. What happens if all the digits of the number are the same (e.g., 5555)?
5. How does the Kaprekar process relate to this problem?

Tip: When rearranging digits for the highest and lowest values, always sort in descending and ascending order, respectively.