reCaptcha.cmp

<aura:component implements="force:appHostable,flexipage:availableForAllPageTypes,flexipage:availableForRecordHome,force:hasRecordId,forceCommunity:availableForAllPageTypes">
	<ltng:require scripts="{!join(',',
                           $Resource.jQuery_3_1_1)}" 
                  afterScriptsLoaded="{!c.onScriptLoaded}"/>
    
    <aura:attribute name="hasreCaptchaVerified" type="Boolean" default="false" />
    
    <aura:attribute name="hostUrl" type="String" />
    <aura:attribute name="recaptchaPageName" type="String" default="apex/reCaptcha"/>
    <aura:handler name="init" value="{!this}" action="{!c.doInit}"/>
    
     <div>
        <div class="slds-align_absolute-center container">
            <lightning:layout horizontalAlign="center" verticalAlign="center" multipleRows="true" class="slds-box outer-box">
                <!-- Captcha Section-->
                <lightning:layoutItem size="12" class="slds-m-top_small recaptcha-section">
                    <iframe src="{!v.hostUrl + '/' + v.recaptchaPageName}" frameborder="0" width="100%" allowtransparency="true" id="recaptchaFrame" class="recaptchaFrame "/>
                </lightning:layoutItem> 
                
                <lightning:layoutItem size="12" class="slds-m-top_small recaptcha-section">
                    <div class="slds-text-color_error">Is Verified : {!v.hasreCaptchaVerified}</div>
                </lightning:layoutItem>
            </lightning:layout>
         </div>
    </div>
    
    
</aura:component>

reCaptchaController.js

({
	onScriptLoaded : function(component, event, helper) {
        jQuery(function($){
            let iframe = $('.recaptchaFrame');  
            iframe = iframe[0];
            iframe.height = '60px';
        });
	},
    doInit : function(component, event, helper) {
        window.addEventListener("message", function(event) {
            let hostOrigin = "https://test-dev-ed--foolish.ap5.visual.force.com"; //window.location.origin
            if (event.origin !==  hostOrigin) {
                return;
            } 
            if (event.data && event.data.action && event.data.action === 'verified') {
				component.set ('v.hasreCaptchaVerified', true);  
            } else if (event.data && event.data.action && event.data.action === 'error') {
				component.set ('v.hasreCaptchaVerified', false);                                                          
            } else if (event.data && event.data.action && event.data.action === 'expired') {
                component.set ('v.hasreCaptchaVerified', false);             
            } else if (event.data && event.data.action && event.data.action === 'loaded') {
                component.set ('v.hasreCaptchaVerified', false); 
            }
            if (event.data && event.data.action && event.data.action === 'heigthChange') {
                let iframe = $('.recaptchaFrame');  
                iframe = iframe[0];
               	iframe.height = event.data.height;
            }
        }, false);
	},
})