how to retrive textfield value in selenium if the value is not present in value attributes?

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I wants to verify value that is present in Display Name field. After entering First Name Display Name will populates automatically. display name value is present in front-end but not present in DOM. I tried with driver.webdriver.findElement(By.id("DisplayName")).getText(); and String abc= driver.webdriver.findElement(By.id("DisplayName")).getAttribute("value");